BARBER: HEREDITY IN CERTAIN MICRO-ORGANISMS. 



31 



the parent type to agglutinins, cultures were tested with the 

 serum of two rabbits, the one immunized with gradually in- 

 creasing doses of new race A, the other immunized in a simi- 

 lar way with the parent type. In both kinds of serum dilu- 

 tions were made ranging from ] in 4000 to 1 in 13,000, and 

 in the rabbit immunized with race A, as high as 1 in 21,000. 

 In all these dilutions, the parent race showed decidedly more 

 sensitiveness to agglutinins when fresh broth cultures were 

 used. Agar cultures showed a less decided difference. Tests 

 were made both microscopically and macroscopically ; con- 

 trols were kept, to eliminate error due to spontaneous clump- 

 ing, and, in order to eliminate the personal equation I sub- 

 mitted the results to two other persons, experienced observers, 

 who independently confirmed my judgment. Many series of 

 tests were made, only one of which I give in the table below. 

 The test was made with the serum of a rabbit inoculated with 

 nine successive inoculations of cultures of race A, the inocula- 

 tion period extending over twenty-five days and ending with 

 a dose of 3.5 cc. of a six-day broth culture. 



Table V. 



Thus it is evident that the parent type is more easily ag- 

 glutinated than the race, whether the agglutinating serum is 

 obtained from an animal immunized to the race or one 

 immunized to the check. This difference between the new 

 type and check may possibly be referred to the more fila- 

 mentous character of the race, and a consequent less motility. 

 While the difference in agglutination is decided in broth cul- 

 tures, it is doubtful in emulsions of agar cultures ; and it 

 will be remembered that in agar the filamentous character of 

 the race is less pronounced. 



The lesions in the inoculated rabbits were insignificant, and 

 there v/as no decided difference between race and type. 



